The present invention relates to a method of operating a drive device and to a corresponding drive device.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
A drive device is used, for example, to provide a drive torque for a motor vehicle, i.e. to provide a drive torque for propelling the motor vehicle. The drive device can include, for example, an internal combustion engine which produces exhaust gas which is conducted through an exhaust tract in the direction of the ambient surroundings of the motor vehicle. Disposed in the exhaust tract is an exhaust gas probe to determine or measure at least one characteristic of the exhaust gas that flows in the exhaust tract. Exhaust gas flows hereby through the exhaust gas probe or sweeps over the exhaust gas probe. For example, the exhaust gas probe can be constructed in the form of a lambda probe, constructed to determine a residual oxygen content in the exhaust gas.
In order to be able to accurately determine the at least one exhaust characteristic with the assistance of the exhaust gas probe, it is necessary for the exhaust gas probe to reach its operating temperature. While this may be realized, of course, by heat transfer from exhaust gas to the exhaust gas probe, this process is very time-consuming. The exhaust gas probe may be heated in a faster way by using a probe heater. In particular, when a cold start of the drive device or internal combustion engine is involved, the provision of a probe heater enables determination of the exhaust characteristic after cold start with adequate accuracy. Suitably, the exhaust gas probe is heated by the probe heater immediately at the start of operation of the drive device, in particular when the internal combustion engine is started. This time instance can be designated as start of heating.
The heating process of the exhaust gas probe can be monitored by measuring the probe temperature of the exhaust gas probe, e.g. with a temperature sensor which may be disposed at the exhaust gas probe. The temperature sensor may be a separate component that is mounted onto the exhaust gas probe, or may be integrated in the exhaust gas probe. To check the exhaust gas probe and the probe heater, it has been proposed to measure the probe temperature after elapse of a certain time interval after start of heating and to compare the probe temperature with a temperature limit value. When the probe temperature falls short of the temperature limit value, the presence of a defect of the probe heater is recognized. However, there may be situations in which the exhaust gas probe has reached at the start of heating a probe temperature which, for example, due to high ambient temperature and/or due to a short stoppage of the drive device, is high enough for the probe temperature to exceed the temperature limit value after elapse of the certain time interval, so that a correctly functioning probe heater is assumed, even though that may, in fact, not be the case.
It would therefore be desirable and advantageous to address these problems and to obviate other prior art shortcomings.